Systems, methods and materials for hydrogen sulfide conversion

ABSTRACT

Systems and methods use bimetallic alloy particles for converting hydrogen sulfide (H 2 S) to hydrogen (H 2 ) and sulfur (S), typically during multiple operations. In a first operation, metal alloy composite particles can be converted to a composite metal sulfide. In a second operation, composite metal sulfide from the first operation can be regenerated back to the metal alloy composite particle using an inert gas stream. Pure, or substantially pure, sulfur can also be generated during the second operation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to U.S. Provisional PatentApplication No. 62/716,705, filed Aug. 9, 2018, and U.S. ProvisionalPatent Application No. 62/734,387, filed Sep. 21, 2018, where the entirecontents of both applications are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to systems and methods for convertinghydrogen sulfide (H₂S) in a gas stream to hydrogen (H₂) and sulfur. Moreparticularly, the present disclosure relates to bimetallic alloys usablein systems and methods for generating hydrogen (H₂) and sulfur streamsfrom hydrogen sulfide (H₂S) streams.

BACKGROUND

Natural gas, petroleum and coal are primarily utilized as energysources. However, sulfur compounds such as hydrogen sulfide (H₂S) withinthese fuels limit their use due to the toxic and corrosive nature ofsuch compounds. For example, exposure to H₂S can be harmful for humanseven at concentrations as low as 10 ppm. In addition, the applicabilityof these fuels as a feedstock for value-added chemicals is also limiteddue to catalyst deactivation as a result of sulfur poisoning.

Currently used processes for removing hydrogen sulfide (H₂S) areintensive and demand high energy. Additionally, currently used processescannot recover H₂ along with sulfur because H₂ is lost in the form ofwater vapor. Furthermore, the performance of solids used in hydrogensulfide (H₂S) processing can deteriorate after a single cycle. Suchsystems are inefficient and can require replenishing the solids afterone or just a few cycles of sulfur capture and regeneration. Therefore,there is a need for an improved process to effectively convert hydrogensulfide (H₂S) into hydrogen (H₂) and sulfur.

SUMMARY

Disclosed herein are systems and methods for converting hydrogen sulfide(H₂S) in a gas stream to hydrogen (H₂) and sulfur. In one aspect, amethod utilizes metal alloy composite particles for converting hydrogensulfide (H₂S) in a gas stream to hydrogen (H₂) and sulfur. The method isa two-step thermochemical decomposition of H₂S into H₂ and sulfur. Thefirst step is referred to as the sulfidation operation, wherein H₂Sreacts with the metal alloy composite particle to form a mixture ofmetal sulfides and produce H₂. The second step is referred to as theregeneration operation, wherein the mixture of metal sulfides issubjected to a high temperature and gas input stream to remove thecaptured sulfur and regenerate the metal alloy composite particle.Thereby, separate H₂ and sulfur streams are produced from an inputstream including H₂S. Compared to the conventionally used Claus processfor sulfur recovery, which only produces sulfur and no H₂, the disclosedmethod is economically favorable. It is also beneficial to theenvironment as it converts a toxic, poisonous, and corrosive H₂S gas tovaluable chemicals H₂ and sulfur.

There is no specific requirement that a material, technique or methodrelating to H₂S conversion include all of the details characterizedherein, in order to obtain some benefit according to the presentdisclosure. Thus, the specific examples characterized herein are meantto be exemplary applications of the techniques described, andalternatives are possible. Other aspects of the disclosure will becomeapparent by consideration of the detailed description and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of an exemplary system for H₂Sconversion to H₂ and S.

FIG. 2 shows a schematic diagram of another exemplary system for H₂Sconversion to H₂ and S.

FIG. 3 shows a schematic diagram of another exemplary system for H₂Sconversion to H₂ and S.

FIG. 4 shows an example method for H₂S conversion to H₂ and S.

FIG. 5 shows an example method for preparing a metal alloy compositeparticle for use in H₂S conversion to H₂ and S.

FIG. 6 shows the X-ray diffraction analysis of the iron-chromium metalalloy composite particle obtained after preparation in a fixed bedreactor.

FIG. 7 shows H₂S conversion for an iron-chromium alloy compositeparticle over five sulfidation-regeneration operations where the gashourly space velocity for first two sulfidation operations was 5000 hr⁻¹and for the last three was 2580 hr⁻¹.

FIG. 8 shows X-ray diffraction analysis of solids in a fixed bed reactorafter five sulfidation-regeneration operations.

FIG. 9 shows the X-ray diffraction analysis of solids after run 1 in afixed bed reactor.

FIG. 10 shows the X-ray diffraction analysis of solids after run 2 inthe fixed bed reactor used to obtain data shown in FIG. 9.

FIG. 11 shows calculated thermodynamic values of H₂S fractionalconversion as a function of iron monosulfide:chromium monosulfide molarratio.

FIG. 12 shows calculated thermodynamic values for molar composition ofiron monosulfide, chromium monosulfide and iron-chromium thiospinel as afunction of iron monosulfide:chromium monosulfide molar ratio.

FIG. 13 shows the X-ray diffraction analysis of Fe—Cr alloy with MoS₂secondary material after reaction with 0.9% H₂S at 800° C.

FIG. 14 shows the X-ray diffraction analysis of Fe—Cr alloy with MoS₂secondary material and SiO₂ support material after reaction with 0.9%H₂S at 800° C.

FIG. 15 shows H₂S conversion over 12 consecutivesulfidation-regeneration cycles with Fe—Cr alloy containing 20 wt %MoS₂.

FIG. 16 shows H₂S conversion as a function of pressure at 400° C. asobtained by using FactSage 7.3 software.

DETAILED DESCRIPTION I. Definitions

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art. In case of conflict, the present document, includingdefinitions, will control. Example methods and materials are describedbelow, although methods and materials similar or equivalent to thosedescribed herein can be used in practice or testing of the presentdisclosure. The materials, methods, and examples disclosed herein areillustrative only and not intended to be limiting.

The terms “comprise(s),” “include(s),” “having,” “has,” “can,”“contain(s),” and variants thereof, as used herein, are intended to beopen-ended transitional phrases, terms, or words that do not precludethe possibility of additional acts or structures. The singular forms“a,” “an” and “the” include plural references unless the context clearlydictates otherwise. The present disclosure also contemplates otherembodiments “comprising,” “consisting of” and “consisting essentiallyof,” the embodiments or elements presented herein, whether explicitlyset forth or not.

The modifier “about” used in connection with a quantity is inclusive ofthe stated value and has the meaning dictated by the context (forexample, it includes at least the degree of error associated with themeasurement of the particular quantity). The modifier “about” shouldalso be considered as disclosing the range defined by the absolutevalues of the two endpoints. For example, the expression “from about 2to about 4” also discloses the range “from 2 to 4.” The term “about” mayrefer to plus or minus 10% of the indicated number. For example, “about10%” may indicate a range of 9% to 11%, and “about 1” may mean from0.9-1.1. Other meanings of “about” may be apparent from the context,such as rounding off, so, for example “about 1” may also mean from 0.5to 1.4.

Definitions of specific functional groups and chemical terms aredescribed in more detail below. For purposes of this disclosure, thechemical elements are identified in accordance with the Periodic Tableof the Elements, CAS version, Handbook of Chemistry and Physics, 75thEd., inside cover, and specific functional groups are generally definedas described therein.

For the recitation of numeric ranges herein, each intervening numberthere between with the same degree of precision is explicitlycontemplated. For example, for the range of 6-9, the numbers 7 and 8 arecontemplated in addition to 6 and 9, and for the range 6.0-7.0, thenumber 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, and 7.0 areexplicitly contemplated. For example, when a pressure range is describedas being between ambient pressure and another pressure, a pressure thatis ambient pressure is expressly contemplated.

II. Metal Alloy Composite Particles

Disclosed herein are metal alloy composite particles for use in systemsand methods for converting H₂S into hydrogen (H₂) and sulfur (S).Typical metal alloy composite particles disclosed and contemplatedherein include metal alloy material, secondary material, and supportmaterial. Without being bound by a particular theory, it is believedthat each component plays a role in H₂S processing. For instance, themetal alloy material captures sulfur generated from dissociation of H₂S.Additionally, efficient capture of sulfur appears to be linked to theformation of spinel phase, which thermodynamically favors near, orcomplete, sulfur capture. The secondary material forms active centers onthe surface of the metal alloy composite particle where it catalyticallydissociates H₂S to H₂ and sulfur. The metal alloy material is dispersedin the support material to prevent sintering and agglomeration of themetal alloy composite particle, which could reduce the regenerability ofthe particle.

A. Metal Alloy Material

Metal alloy material comprises a first metal component and a secondmetal component. The first metal component comprises a first metal, afirst metal sulfide comprising the first metal, a first metal oxidecomprising the first metal, or combinations thereof. The second metalcomponent comprises a second metal, a second metal sulfide comprisingthe second metal, a second metal oxide comprising the second metal, orcombinations thereof.

Usually, each of the first metal and second metal is selected from: iron(Fe), chromium (Cr), nickel (Ni), Zinc (Zn), cobalt (Co), manganese (Mn)and copper (Cu). For example, the first metal component may compriseiron and the second metal component may comprise chromium. In someembodiments, the first metal component comprises iron sulfide and thesecond metal component comprises chromium sulfide.

The metals of the metal alloy material may be dispersed uniformly asthis results in high conversion of H₂S to H₂ and also improves theregenerability of the metal alloy composite particle. Non-uniformdispersion and/or a layered structure may result in diffusionlimitations of H₂S in the metal alloy composite particle product layerand lower the reaction kinetics.

B. Secondary Material

The metal alloy composite particle may further comprise one or moresecondary material components. In some instances, secondary material isa dopant, as that term is typically understood in the art. In someinstances, secondary material has similar properties to a dopant and/orimparts similar characteristics as a dopant, but exists as a differentphase. In various implementations, the secondary material is disperseduniformly along the surface of the particle and is surrounded by thealloy material.

Typically, secondary material is in the form of MS_(x), where M is ametal, S is sulfur, and x is in the range of values between 0 and 2. Forexample, x maybe 0, 1, or 2. X may also be a non-integer value. Forexample, x may be 0.5 or 1.5. Example metals M include, but are notlimited to, molybdenum, nickel, cobalt, manganese, tungsten, vanadiumand combinations thereof.

The secondary material may be a sulfide. For example, the secondarymaterial may be a molybdenum disulfide, a nickel sulfide, a cobaltsulfide, a manganese sulfide, a tungsten sulfide, vanadium sulfide orcombinations thereof.

In some instances, secondary material is a metal oxide. For example, thesecondary material may be a molybdenum oxide, a nickel oxide, a cobaltoxide, a manganese oxide, a tungsten oxide, a vanadium oxide orcombinations thereof.

C. Support Material

The metal alloy composite particle may further comprise one or moresupport materials. The support material can be any inert material. Theone or more support materials can be metals, metal oxides, non-metaloxides, zeolites or metal organic frameworks. Suitable support materialsinclude, but are not limited to, alumina, bauxite, titania, silicon,zirconium, and alumina silicate. For example, the support material maybe an aluminum oxide, a silicon oxide, a titanium oxide, a zirconiumoxide, and the like.

D. Example Amounts and Sizes

The metal alloy composite particle may comprise any suitable ratio ofcomponents to produce the desired effect. For example, the metal alloycomposite particle may comprise 10-95% by weight of the first metalcomponent, 5-80% by weight of the second metal component, and 0-50% byweight of the secondary material. For example, the metal alloy compositeparticle may comprise 10-95% by weight iron, 5-80% by weight chromium,and 0-50% by weight of the secondary material.

For example, the metal alloy composite particle may comprise about 10%,about 15%, about 20%, about 25%, about 30%, about 40%, about 45%, about50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%,about 85%, about 90%, or about 95% by weight of the first metalcomponent. In various implementations, the metal alloy compositeparticle comprises 10 wt % to 50 wt %; 40 wt % to 95 wt %; 20 wt % to 75wt %; 30 wt % to 50 wt %; 35 wt % to 65 wt %; 50 wt % to 80 wt %; or 40wt % to 70 wt % of the first metal component.

The metal alloy composite particle may comprise about 5%, about 10%,about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%,or about 80% by weight of the second metal component. In variousimplementations, the metal alloy composite particle comprises 5 wt % to50 wt %; 45 wt % to 80 wt %; 15 wt % to 65 wt %; 10 wt % to 35 wt %; 35wt % to 60 wt %; 60 wt % to 80 wt %; or 20 wt % to 45 wt % of the secondmetal component.

The metal alloy composite particle may comprise about 0%, about 5%,about 10%, about 15%, about 20%, about 25%, about 30%, about 40%, about45%, or about 50% by weight of the secondary material. In variousimplementations, the metal alloy composite particle comprises 5 wt % to45 wt %; 10 wt % to 50 wt %; 20 wt % to 40 wt %; 30 wt % to 50 wt %; 10wt % to 20 wt %; 15 wt % to 35 wt %; or 20 wt % to 30 wt % of thesecondary material.

The metal alloy composite particle has a diameter of between about 100μm and about 10 mm. For example, the metal alloy composite particle mayhave a diameter of about 100 μm to about 10 mm, about 1 mm to about 9mm, about 2 mm to about 8 mm, about 3 mm to about 7 mm, or about 4 mm toabout 6 mm.

The grain size of the first metal component, the second metal component,and the secondary material can vary depending on the type of materialused and the temperature at which the metal alloy composite particle issintered. A smaller grain size is preferred as it results in fasterreaction kinetics due to elimination of diffusion limitations in themetal alloy composite particle.

The range of grain size for the first metal component, the second metalcomponent, and the secondary material can be between 10⁻³ μm to 50 μm.For example, the grain size can be about 10⁻³ μm, about 10⁻² μm, about 1μm, about 5 μm, about 10 μm, about 15 μm, about 20 μm, about 25 μm,about 30 μm, about 35 μm, about 40 μm, about 45 μm, or about 50 μm.

Another parameter that affects the reaction kinetics is the porosity ofthe metal alloy composite particle which determines the gas diffusionwithin the metal alloy composite particle. Porosity of the metal alloycomposite particle is proportional to the concentration of supportmaterial and it can be in the range of 10⁻³ to 5 cm³/g. The surface areaof the metal alloy composite particle is dependent on the grain size aswell as the porosity and is in the range of 0.1 to 100 m²/g.

III. Systems and Methods for Converting H₂S into Hydrogen (H₂) andSulfur

Disclosed herein are systems and methods for converting H₂S intohydrogen (H₂) and sulfur. The system for converting H₂S into hydrogen(H₂) and sulfur may comprise multiple reactors. For example, the systemmay comprise a sulfidation reactor and a regeneration reactor. Theconditions in each of the sulfidation reactor and the regenerationreactor are modified as described below to ensure that the appropriatesulfidation and regeneration reactions occur in each reactor. In otherembodiments, the system may comprise one reactor. The conditions in thesingle reactor may be modified such that the sulfidation andregeneration operations can occur in the single reactor.

Broadly speaking, the disclosed systems and methods reduce the amount ofH₂S in the input gas stream. For example, the disclosed method can beused to reduce the amount of H₂S in the gas stream to below 100 ppm. Forexample, the disclosed method can be used to reduce the amount of H₂S inthe gas stream to less than about 100 ppm, less than about 90 ppm, lessthan about 80 ppm, less than about 70 ppm, less than about 50 ppm, lessthan about 40 ppm, less than about 30 ppm, less than about 20 ppm, lessthan about 10 ppm, less than about 5 ppm, less than about 1 ppm, lessthan about 1 ppm, or less than about 0.1 ppm. For example, the disclosedmethod can be used to reduce the amount of H₂S in the gas stream to lessthan 0.1 ppm.

A. Sulfidation Operation

The disclosed method comprises a sulfidation operation. The sulfidationoperation can be performed in a sulfidation reactor. The sulfidationreactor can be a fixed bed reactor, a fluidized bed reactor, aco-current moving bed reactor, or a counter-current moving bed reactor.A moving bed reactor configuration also includes a packed moving bed,staged fluidized bed, a downer and/or a rotary kiln.

The sulfidation operation comprises contacting a first gaseous streamcomprising H₂S with a metal alloy composite particle. The first gaseousstream may further comprise additional gases. For example, theH₂S-containing gas stream can also include CO, H₂, and/or hydrocarbons.Example hydrocarbons include but are not limited to methane, ethane,propane, butane and higher alkanes. The first gaseous stream may containH₂S and additional gases in other proportions or quantities. Usually,the first gaseous stream includes trace amounts or no oxygen (O₂).

The sulfidation operation may be performed at any suitable temperatureto facilitate sulfidation of the metal alloy composite particle. Forexample, the sulfidation operation may be performed at about 100° C. toabout 950° C. For example, the sulfidation operation may be performed atabout 100° C., about 150° C., about 200° C., about 250° C., about 300°C., about 350° C., about 400° C., about 450° C., about 500° C., about550° C., about 600° C., about 650° C., about 700° C., about 750° C.,about 800° C., about 850° C., about 900° C., or about 950° C. In someinstances, the sulfidation operation is performed at about 300° C. toabout 450° C. As another example, the sulfidation operation is performedat about 350° C. to about 400° C.

The equilibrium of sulfidation reaction favors operating at lowertemperatures, but the reaction kinetics is faster at highertemperatures. As such, some embodiments perform the sulfidationoperation at a temperature of 300° C. to 450° C. Performing sulfidationat 300° C. to 450° C. can eliminate the need for cooling and reheatingthe H₂S containing gas stream as is done for conventional H₂S removalprocesses such as Selexol, Rectisol, or amine based processes.

The sulfidation operation may be performed at any suitable pressure. Forexample, the pressure at which sulfidation operation occurs can be about1 atm to about 150 atm. For example, the pressure can be about 1 atm,about 2 atm, about 3 atm, about 4 atm, about 5 atm, about 6 atm, about 7atm, about 8 atm, about 9 atm, about 10 atm, about 15 atm, about 20 atm,about 25 atm, about 30 atm, about 35 atm, about 40 atm, about 45 atm,about 50 atm, about 55 atm, about 60 atm, about 65 atm, about 70 atm,about 75 atm, about 80 atm, about 85 atm, about 90 atm, about 95 atm,about 100 atm, about 105 atm, about 110 atm, about 115 atm, about 120atm, about 125 atm, about 130 atm, about 135 atm, about 140 atm, about145 atm, or about 150 atm. In various instances, the pressure at whichthe sulfidation operation occurs is from 1 atm to 30 atm; 1 atm to 5atm; 1 atm to 60 atm; 5 atm to 20 atm; 2 atm to 10 atm; or 1 atm to 15atm. Generally, the kinetics of the sulfidation reaction appear to befaster at higher pressures and there is not an effect of pressure on theequilibrium of sulfidation reaction.

The kinetic rate of sulfidation reaction determines the gas residencetime in the sulfidation reactor for maximum conversion of H₂S. The gasresidence time can vary from 0.2 seconds to 45 minutes. It is preferredto have the gas residence time between 0.5 s to 15 min. For example, thegas residence time can be around 0.5 seconds, about 1 second, about 30seconds, about 1 minute, about 2.5 minutes, about 5 minutes, about 7.5minutes, about 10 minutes, about 12.5 minutes, or about 15 minutes.

The amount of H₂S gas that can be treated by the disclosed process isdependent on the composition of the metal alloy composite particle. Theratio of gas to metal alloy composite particle that can be used in thedisclosed systems and methods can be about 1:5 to about 10:1.Preferably, the ratio of gas to metal alloy composite particle rangesfrom about 1:2 to about 5:1. For example, the ratio of gas to metalalloy composite particle can be about 1:2, about 1:1, about 2:1, about3:1, about 4:1, or about 5:1.

In the sulfidation operation, the hydrogen sulfide (H₂S) in the firstgaseous input stream reacts in a sulfidation reaction with the metalalloy composite particle to generate hydrogen gas (H₂) and one or moresulfide minerals. The hydrogen gas (H₂) may be collected and stored forfuture use in other processes. The sulfide mineral is selected from thegroup consisting of a metal sulfide, a thiospinel and combinationsthereof. Without being bound by a particular theory, it appears that thepresence of thiospinel is responsible for favorable equilibrium towardsH₂S decomposition and is non-reactive towards other gases that may bepresent in the H₂S containing gas stream. For example, the sulfidemineral may be an iron sulfide, a chromium sulfide, or combinationsthereof. In some embodiments, sulfide mineral comprises FeCr₂S₄.

B. Regeneration Operation

The disclosed method further comprises a regeneration operation.Typically, the regeneration operation occurs at higher temperatures thanthose used during the sulfidation operation. The regeneration operationcan be performed in a regeneration reactor. The regeneration reactor canbe a fixed bed reactor, a fluidized bed reactor, a co-current moving bedreactor, or a counter-current moving bed reactor. A moving bed reactorconfiguration also includes a packed moving bed, staged fluidized bed, adowner and/or a rotary kiln.

The regeneration operation comprises contacting a second gaseous inputstream comprising at least one inert gas with the one or more sulfideminerals generated during the sulfidation operation. The regenerationoperation thereby generates sulfur gas and regenerates the metal alloycomposite particle for subsequent use. The sulfur gas obtained from theregeneration operation can be collected for future use in downstreamapplications. For example, the sulfur gas can be condensed and removedas solid or liquid sulfur based on its downstream application.

The at least one inert gas can include nitrogen, carbon dioxide andcombinations thereof. For example, the at least one inert gas can benitrogen. For example, regeneration operation can comprise contactingFeCr₂S₄ produced during the sulfidation operation with nitrogen gas,thereby regenerating iron sulfide and chromium sulfide and producingsulfur gas.

The regeneration operation may be performed at any suitable regenerationtemperature to facilitate regeneration of the metal alloy compositeparticle. The regeneration temperature is dependent on the sulfurpressure in the regeneration reactor. A lower sulfur pressure in theregeneration reactor favors the equilibrium towards removal of sulfurand hence lower regeneration temperatures can be used. The regenerationtemperatures can vary from 500° C. to 1100° C. For example, theregeneration operation may be performed at about 750° C., about 800° C.,about 850° C., about 900° C., about 950° C., about 1000° C., about 1050°C., or about 1100° C. In various implementations, the regenerationtemperature may be from 600° C. to 1000° C.; from 700° C. to 1100° C.;from 800° C. to 1000° C.; or from 700° C. to 900° C.

The regeneration operation may be performed under vacuum. Alternatively,the regeneration operation may be performed under pressure conditions.The pressure conditions in the regeneration reactor can range from 1 atmto 150 atm. For example, the pressure can be about 1 atm, about 2 atm,about 3 atm, about 4 atm, about 5 atm, about 6 atm, about 7 atm, about 8atm, about 9 atm, about 10 atm, about 15 atm, about 20 atm, about 25atm, about 30 atm, about 35 atm, about 40 atm, about 45 atm, about 50atm, about 55 atm, about 60 atm, about 65 atm, about 70 atm, about 75atm, about 80 atm, about 85 atm, about 90 atm, about 95 atm, about 100atm, about 105 atm, about 110 atm, about 115 atm, about 120 atm, about125 atm, about 130 atm, about 135 atm, about 140 atm, about 145 atm, orabout 150 atm.

In some instances, a high gas:solids ratio is employed for theregeneration operation as it keeps the sulfur pressure low in theregeneration reactor, thus enabling a relatively lower regenerationtemperature. For example, the gas:solids molar ratio can range from 0.2to 10, preferably, from 0.5 to 5. For example, gas:solids molar ratiocan be about 1:2, about 1:1, about 2:1, about 3:1, about 4:1, or about5:1.

A low gas residence time is preferred to aid in maintaining low sulfurpressures in the regeneration reactor. The gas residence time can varyfrom 0.05 seconds to about 5 minutes, preferably from about 0.1 s toabout 2 minutes. For example, the gas residence time can be about 0.05seconds, about 0.1 seconds, about 1 second, about 5 seconds, about 10seconds, about 30 seconds, about 60 seconds, about 90 seconds, about 2minutes, about 3 minutes, about 4 minutes, or about 5 minutes.

The disclosed method can be operated in batch operational mode, asemi-batch operational mode, or continuous operation mode. The methodcan further comprise contacting the metal alloy composite particleproduced following the regeneration operation, (i.e. the regeneratedmetal alloy composite particle) with a subsequent first gaseous inputstream, thus repeating the process of isolating hydrogen gas (H₂) andsulfur from an H₂S containing feed stream. The hydrogen gas (H₂)production performance of the regenerated metal alloy composite particlecan be similar to the performance of the original metal alloy compositeparticle.

C. Example Configurations of Systems and Method for H₂S Conversion

FIG. 1, FIG. 2, and FIG. 3 are schematic diagrams of exemplary systemsfor conversion of H₂S. Various aspects regarding possible operatingconditions for the exemplary systems, such as temperature, pressure,residence time, etc., as well as exemplary metal alloy compositeparticles usable in the exemplary systems, are described in greaterdetail above, apply to the following discussion, and are not repeatedbelow for the purpose of conciseness.

FIG. 1 shows a schematic diagram of exemplary system 100 for H₂Sconversion to H₂ and S. As shown in FIG. 1, system 100 comprisessulfidation reactor 102 and regeneration reactor 104. The sulfidationreactor 102 includes a metal alloy composite particle as disclosedherein. An H₂S containing gas stream is provided into the sulfidationreactor 102, resulting in the formation of hydrogen gas (H₂) and one ormore sulfide minerals. The hydrogen gas (H₂) is collected, and the oneor more sulfide minerals are provided to the regeneration reactor 104.An inert gas stream is provided into the regeneration reactor 104,resulting in the formation of sulfur gas and regeneration of the metalalloy composite particle. The metal alloy composite particle is providedback to the sulfidation reactor 102 and the sulfur gas is collected.

FIG. 2 shows a schematic diagram of exemplary system 200 for H₂Sconversion to H₂ and S. In system 200, alloy material reacts with H₂S orH₂S containing gas (stream number 251) in reactor 202. The alloymaterial with the captured sulfur is then transferred to reactor 204,where the alloy material is regenerated by an inert gas such as N₂. TheN₂ sent to reactor 204 (stream number 252) is preheated with the gasoutlet from reactor 204 and additional heating may be provided byburning fuel gas. The sulfur is removed in reactor 204, and the sulfuris then condensed by cooling with water and finally separated from N₂ ina gas-liquid separator 206. The regenerated solids are sent to reactor208, where they are fluidized with heated N₂ (stream number 253) andthen transported back to reactor 202. N₂ and solids separation occurs inthe cyclone separator 210. The separated N₂ is recycled back to reactor204 (stream number 255). The separated N₂ can also be sent to thereactor 208 for fluidization (stream number 256) or to an outlet ofreactor 204 (stream number 257) for pushing the solids into reactor 208.H₂ is injected as a zone seal gas to prevent gas mixing between reactor202, reactor 204 and cyclone separator 210. This is important to reducedownstream H₂ product gas purification.

Reactors 202 and 204 are operated as countercurrent moving bed reactors.The residence time of gas and solids in reactors 202 and 204 may becontrolled such that there is complete H₂S conversion in reactor 202 andcomplete regeneration in reactor 204. Reactor 208 is a fluidized bedreactor and its main purpose is for transporting solids via a riser backto reactor 202.

FIG. 3 shows a schematic diagram of exemplary system 300 for H₂Sconversion to H₂ and S. System 300 includes three fixed bed reactors. Ata given time, sulfidation occurs in reactor 302, regeneration in reactor304 and reactor 306 is on standby. H₂S or H₂S containing gas (streamnumber 351) is sent to reactor 302 and the outlet gas is sent to apressure swing adsorption (PSA) unit 308 to produce high purity Hz. N₂(stream number 352) is heated in two stages by preheater and then byfuel gas, before being sent to reactor 304 for removing sulfur from thesolids. The sulfur removed is then condensed out in a sulfur condenserand the cooled down N₂ is recycled (stream number 353) back to thepreheater. Once reactor 302 is saturated with sulfur, it is switched toregeneration with the use of remote operated valves. Reactor 306 isswitched to sulfidation as it contains regenerated solids and reactor304 is switched to standby. The number of reactors and switching time iscontingent on the gas flow rates and amount of solids used in each ofthe reactors.

FIG. 4 shows an example method 400 for H₂S conversion to H₂ and S.Method 400 begins by contacting the metal alloy composite particle (suchas a metal alloy composite particle prepared by example method 500) withan H₂S containing gas stream in a sulfidation reactor (operation 402).Operation 402 results in the formation of hydrogen gas (H₂) and one ormore metal sulfides. Next, the hydrogen gas (H₂) is collected (operation404). The remaining sulfide minerals are provided to the regenerationreactor (operation 406). The sulfide minerals are contacted with aninert gas in the regeneration reactor (operation 408). Operation 408results in the formation of sulfur gas and regeneration of the metalalloy composite particle. The sulfur gas is collected (operation 410).The regenerated metal alloy composite particle is provided back to thesulfidation reactor (operation 412). The process then begins again bycontacting the regenerated metal alloy composite particle with an H₂Scontaining gas stream in the sulfidation reactor (operation 414). Theprocess may be repeated for any desired number of cycles.

D. Example Improvements and Industrial Applications

The systems and methods disclosed herein result in conversion of apoisonous, toxic and corrosive gas like H₂S to highly valuable chemicalslike hydrogen (H₂) and sulfur (S₂). The methods can use a two-reactorsystem with few heat exchangers, or a one reactor system, to produce H₂and sulfur from H₂S. Therefore, there are capital cost benefits in usingfewer processing units compared to typically used methods. Moreover, themethods described herein are robust towards other gases, like carbonmonoxide, hydrogen and hydrocarbons, commonly found in industrialprocess streams that contain H₂S. Therefore, the instant systems andmethods typically do not require separating these gases before treatingH₂S, which allows for savings in energy and capital costs that areusually involved with separating these gases.

The methods described herein allow H₂S to be treated at very hightemperatures. Treating at high temperatures reduces or eliminates theneed for cooling and reheating the H₂S containing gas stream as istypically done for conventional H₂S removal processes such as Selexol,Rectisol, or amine based processes. Moreover, the disclosed methods andprocess utilize solids with high recyclability, resulting in thecapacity for long term use and minimal replacement and waste managementcosts.

The methods described herein can be used in multiple industrialapplications. For example, the methods described herein can be used forcoal gasification to produce synthesis gas (syngas). The majorcomponents of synthesis gas are carbon monoxide (CO) and H₂ and this gasstream is at >500° C. This gas can be directly sent to the processdisclosed herein without the need for cooling the gas stream or removingCO or Hz.

The methods described herein can be used in natural gas processingmethods. H₂S is typically removed from natural gas before it is sent tocatalytic processes, such as steam methane reforming, to produce syngasand Hz. Steam methane reforming occurs in temperature range of 700-1000°C. and requires very low concentrations of H₂S in the gas stream. Themethods described herein can be used to reduce H₂S concentrations in agas stream to the desired values before use of the gas stream incatalytic processes such as steam methane reforming.

The methods described herein can be used in crude oil processing. Sulfurfrom crude oil is typically removed in a hydrodesulfurization unit bytreating it with H₂ in a temperature range from 300-400° C. The gas fromthis unit is a mixture of H₂S and Hz. The gas from such ahydrodesulfurization unit can be directly treated by a method describedherein to produce H₂ and sulfur.

IV. Systems and Methods for Producing Metal Alloy Composite Particles

Further disclosed herein are systems and methods for producing metalalloy composite particles. The metal alloy composite particle may beproduced by mixing the first metal component and the second metalcomponent in their respective desired amounts. The mixture of the firstmetal component and the second metal component is reacted with H₂S at atemperature of about 300° C. to about 900° C. For example, the mixtureof the first metal component and the second metal component can bereacted with H₂S at a temperature of about 300° C., about 350° C., about400° C., about 450° C., about 500° C., about 550° C., about 600° C.,about 650° C., about 700° C., about 750° C., about 800° C., about 850°C., or about 900° C. The time of the reaction is dependent on the amountof first metal component and the second metal component used. A mixtureof thiospinel and higher metal sulfides is formed at the end of thereaction.

Nitrogen is then passed over the reacted mixture in a temperature rangeof about 600° C. to about 1200° C. For example, nitrogen may be passedover the reacted mixture at a temperature of about 600° C., about 650°C., about 700° C., about 750° C., about 800° C., about 850° C., about900° C., about 950° C., about 1000° C., about 1050° C., about 1100° C.,about 1150° C., or about 1200° C.

Subsequently, a secondary material can be mixed together with the alloymaterial. Additionally, a support material can be mixed together withthe alloy material. The mixture is then sintered at a temperature ofabout 700° C. to about 1400° C. For example, the mixture may be sinteredat a temperature of about 700° C., about 750° C., about 800° C., about850° C., about 900° C., about 950° C., about 1000° C., about 1050° C.,about 1100° C., about 1150° C., about 1200° C., about 1250° C., about1300° C., about 1350° C., or about 1400° C.

FIG. 5 shows an example method 500 for preparing a metal alloy compositeparticle for use in the disclosed method of H₂S conversion to Hz and S.Method 500 begins by mixing the first metal component and the secondmetal component (operation 502). The mixture of the first metalcomponent and the second metal component is reacted with a gascontaining H₂S (operation 504). Next, nitrogen is passed over themixture (operation 506). Next, a secondary material (operation 508) anda support material (510) are added to the mixture. Lastly, the mixtureis sintered (operation 512).

V. Experimental Examples Example 1 Iron-Chromium (Fe—Cr) Metal AlloyPreparation

Iron sulfide (FeSx, 0<x<2) and chromium sulfide (CrSy, 0<y<1.5) weremixed in a molar ratio of 1:2. Iron oxide, chromium oxide, iron metal,chromium metal or a mixture of these compounds can also be taken as thestarting material. The said mixture was reacted with gas containing H₂Sat a concentration of 0.9% in a fixed bed reactor kept in a horizontaltube furnace. The said gas containing H₂S was reacted at a temperatureof 800° C. After reaction with H₂S, the gas was switched to N₂ and thetemperature was increased to 950° C. FIG. 6 shows the X-ray diffraction(XRD) analysis of the solid sample obtained after cooling down to roomtemperature under the N₂. The presence of an Fe—Cr alloy is clearlyvisible from the XRD spectra.

Example 2 H₂S Conversion by Exemplary Metal Alloy Composite Particles

FIG. 7 shows the performance of an Fe—Cr alloy in a fixed bed reactorfor H₂S conversion to Hz and S over multiple sulfidation andregeneration operations. The temperatures of sulfidation andregeneration operations were 800° C. and 950° C., respectively. A 0.9%H₂S/N₂ gas was injected into the fixed bed reactor during sulfidationoperation and N₂ was injected during the regeneration operation. The gashourly space velocity (GHSV) for sulfidation operation for the first andsecond cycle was 5000 hr-1, whereas, GHSV for third, fourth and fifthsulfidation operation was 2580 hr-1. The concentration of gas leavingthe fixed bed reactor was measured using a Siemens CALOMAT 6E H₂analyzer. The gas was also intermittently sampled by Interscan's ModelRM17-500m Toxic gas monitor to measure H₂S concentration in the reactoroutlet. H₂S conversion was calculated based on the H₂ concentrationdetected by the H₂ analyzer. A high H₂S conversion over multiple GHSVsrepeated over several sulfidation-regeneration operations demonstratesexcellent performance and recyclability of the Fe—Cr alloy. FIG. 8 showsthe presence of iron-chromium thiospinel (FeCr₂S₄) via XRD analysis ofthe solids after the fifth sulfidation operation.

Table 1 shows the inlet and outlet composition of gas sent duringsulfidation operation for two different runs at 800° C. in a fixed bedreactor containing Fe—Cr alloy. In run 1, 50 ml/min of 0.9% H₂S/N₂ and46.95 ml/min 9.6% methane (CH₄)/19% C0/81.4% N₂ was co-injected into thefixed bed reactor for 30 min. The reactor outlet gas concentration wasmeasured using a Siemens Ultramat 23 gas analyzer to measure CO, CO₂ andCH₄ concentrations and Siemens Calomat 6E gas analyzer to measure H₂concentration. In run 2, 100 ml/min of 0.9% H₂S/N₂ and 100 ml/min of100% H₂ was co-injected into the fixed reactor for 30 min. The reactoroutlet gas concentration was measured using a Siemens CALOMAT 6E H₂analyzer. The fact that the inlet and outlet gas compositions are thesame indicates that CH₄, CO and H₂ do not react with the Fe—Cr alloy.

TABLE 1 Inlet and outlet gas composition for two experiments in a fixedbed reactor at 800° C., (*based on XRD analysis results and massbalance). Run 1 Run 2 Inlet gas Outlet gas Inlet gas Outlet gascomposition composition composition composition Gases (%) (%) (%) (%)*H₂S 0.46 0.009 0.45 0 CH₄ 9.28 9.28 0 0 CO 4.55 4.55 0 0 H₂ 0 0.451 5050.45 N₂ 85.71 85.71 49.55 49.55

XRD analysis of the sample at the end of the Run 1 and Run 2 shown inFIG. 9 and FIG. 10, respectively, proved that sulfur in H₂S was capturedby the Fe—Cr alloy and FeCr₂S₄ was formed.

FIG. 11 and FIG. 12 illustrate the favorable effect that FeCr₂S₄formation has on the thermodynamic equilibrium conversion of H₂S to Hz.Equilib module in FactSage 7.1 software was used to perform thethermodynamic calculations. A basis of 1 mol of iron monosulfide (FeS)and 1 mol of H₂S was selected whereas the moles of chromium monosulfide(CrS) were varied. In FIG. 12, FeCr₂S₄ is observed to form at FeS:CrSmolar ratio of 2 and from that value of ratio onwards the correspondingH₂S fractional conversion to H₂ is 1 as seen in FIG. 11.

Example 3 Fe—Cr Bimetallic Alloy Comparison with Fe—Cr Bimetallic Alloyand MoS₂ Secondary Material

Table 2 shows the comparison of H₂S conversion by Fe—Cr alloy material(sample 1) against that of Fe—Cr alloy material added with MoS₂secondary material (sample 2). The primary phases present in the Fe—Cralloy based on XRD analysis are FeCr₂S₄ (31.3 wt %), FeCr or 410 Lstainless steel (63.4 wt %) and Cr₂O₃ (5.2 wt %). The composition ofsample 2 is 50 wt % of the Fe—Cr alloy (sample 1) and 50 wt % MoS₂. Forboth samples, powder of size less than 125 microns was placed in betweenquartz wool and supported in the heated region of a 0.5 inch innerdiameter ceramic reactor. The samples were heated to a temperature of800° C. under nitrogen followed by reaction with 0.9% H₂S in thesulfidation step, where the gas flow rate was varied to test differentgas hourly space velocities (GHSVs). The sulfidation step was followedby a regeneration step under nitrogen flow at 950° C. Multiplesulfidation and regeneration steps were conducted for both the sampleswhere different GHSVs were tested during the sulfidation step. Thereactor outlet gas composition was measured using a Siemens CALOMAT 6EH₂ analyzer for H₂ concentration and intermittently using Interscan'sModel RM17-500m Toxic gas monitor for H₂S concentration. A high H₂Sconversion for sample 2 indicates faster reaction kinetics of the solidsample with H₂S, which may be a result of addition of MoS₂ as thesecondary material. The XRD analysis of Sample 2 after reaction is shownin FIG. 13, where FeCr₂S₄ and MoS₂ phases have been marked.

TABLE 2 H₂S conversion comparison between sample 1 and sample 2 at 800°C. with 0.9% H₂S H₂S conversion (%) GHSV (hr⁻¹) Sample 1 Sample 2 1200083.33 100 15000 73.24 88.55 18000 61.04 78.84

Example 4 Fe—Cr Bimetallic Alloy Comparison with Fe—Cr Bimetallic Alloywith MoS₂ Secondary Material and SiO₂ Support Material

Table 3 compares the H₂S conversion of Fe—Cr alloy (sample 3) with thatof Fe—Cr alloy with added MoS₂ secondary material and SiO₂ as thesupport material (sample 4). Based on XRD analysis, sample 3 has FeCr₂S₄(37.3 wt %), FeCr or 410 L stainless steel (25 wt %) and Fe_(0.879)S (37wt %) as the major phases. The composition of sample 4 is 37.5 wt %Fe—Cr alloy (sample 3), 25 wt % MoS₂ and 37.5 wt % SiO₂. Multiplesulfidation-regeneration steps were conducted on both the samples in a0.5 inch inner diameter ceramic reactor. The sulfidation temperature was800° C. and regeneration temperature was 950° C. H₂S conversion wasmeasured during one of the sulfidation steps at the same H₂S flow rateper unit active material weight for both the samples. The activematerial consists of both the Fe—Cr alloy as well as the secondarymaterial-MoS₂. The reactor outlet gas composition was measured using aSiemens CALOMAT 6E H₂ analyzer for H₂ concentration and intermittentlyusing Interscan's Model RM17-500m Toxic gas monitor for H₂Sconcentration. The H₂S conversion of sample 4 is slightly higher thansample 3 which may be a result of faster reaction kinetics with H₂S. TheH₂S conversion for sample 4 may be further enhanced by varying itsalloy, secondary material and/or support material composition. FIG. 14shows the FeCr₂S₄ and MoS₂ phases present in sample 4 based on XRDanalysis.

TABLE 3 H₂S conversion comparison between sample 3 and sample 4 at 800°C. with 0.9% H₂S 0.9% H₂S flow rate/weight of H₂S conversion (%) activematerial (ml/min · g) Sample 3 Sample 4 128 83.33 86.11

Example 5 Fe—Cr Bimetallic Alloy with MoS₂ Secondary Material withDifferent Gas Mixtures

Fe—Cr alloy with 20 wt % MoS₂ was tested with four different gasmixtures, shown in Table 4 below, and at a pressure of 1.8 bar.

TABLE 4 Reaction performance of Fe—Cr alloy with 20 wt % MoS₂ withdifferent gas mixtures [*HCs = (1.04 vol %) 1,3-butadiene, (2.02 vol %)2-butene, (6.04 vol %) hydrogen, (7.25 vol %) methane, (2.07 vol %)n-pentane, (2 vol %) propylene, (79.58 vol %) ethylene]. Gas hourlyspace velocity Mixture Inlet gas composition (%) GHSV Reaction No. CH₄CO H₂ CO₂ H₂S N₂ HCs* (hr⁻¹) performance 1 7.08 3.52 — — 0.56 88.84 —8800 95-100% H₂S conversion for 45 min No oxides in solids 2 — — 75 —0.25 24.75 — 24000 95-100% H₂S conversion for 15 min 3 — — — 25 0.6774.33 — 10000 95-100% H₂S conversion for 36 min No oxides in solids 4 —— — — 0.4 43.89 55.71 12000 95-100% H₂S conversion for 23 min No carbondeposition

The Fe—Cr alloy was used in powder form with particle size <125 micronsin a ceramic fixed bed reactor of 0.5 inch inner diameter. The reactorwas heated using an electrical heater to a temperature of 400° C. underthe flow of N₂. Once the reactor temperature reached 400° C., mixing ofthe various gas compositions mentioned in Table 4 was started.

Gas hourly space velocity (GHSV) shown in the second to last column inTable 4 was calculated based on the gas flow rate and metal alloycomposite bed volume. H₂S conversion was measured based on measuringsulfur content in the alloy before and after the reaction. Sulfurcontent was measured using a Thermo Fisher Scientific TS 3000 totalsulfur analyzer (Waltham, Mass.). The H₂S conversion for the differentgas mixtures is shown in the last column of Table 4.

For gas mixtures 1 and 3, no oxides were observed in the solids from XRDanalysis. Moreover, no carbon deposition was observed for gas mixture 4based on XRD analysis of the reacted sample. Therefore, the alloyappears to be resistant to oxidation with CO₂ and CO along with beingresistant to carbon deposition in presence of hydrocarbons at 400° C.This resistance allows for application of the alloy for H₂S capture froma variety of process streams that can contain any of the contaminantsmentioned in Table 4.

Example 6 Recyclability of Fe—Cr Alloy Sample

Recyclability of exemplary Fe—Cr alloy particles was tested byperforming twelve consecutive sulfidation-regeneration cycles over Fe—Cralloy with 20 wt % MoS₂ in a fixed bed reactor. The fixed bed reactorwas made of ceramic material and had an inner diameter of 0.5 inch. Thesulfidation temperature was 400° C. and the regeneration temperature was950° C. The gas feed during sulfidation step was 0.9% H₂S balanced withN₂ at a GHSV of 1490 hr⁻¹. The reactor pressure was 1 bar for all thesulfidation steps except for the 8th step where the reactor pressure wasincreased to 1.8 bar. H₂S conversion was calculated based on the H₂concentration measured using a Siemens CALOMAT 6E H₂ analyzer. Nearly100% conversion (FIG. 15) was observed over the 12 cycles, whichindicated excellent recyclability of the Fe—Cr alloy.

Example 7 Effect of Pressure on H₂S Conversion with Fe—Cr Alloy

Effects of pressure on H₂S conversion with a Fe—Cr alloy were tested.Thermodynamic calculations conducted in FactSage 7.3 softwaredemonstrate no effect of pressure on the conversion of H₂S. The H₂Sinput was 1 mole, whereas, FeS and CrS input was 1 mole and 2 moles,respectively. FIG. 16 shows that at 400° C., H₂S conversion is nearly100% for all the pressures between 1 to 60 atm.

Experimentally, pressure was observed to improve the kinetics of H₂Sconversion. Fe—Cr alloy powder of particle size <125 microns was reactedwith 0.9% H₂S in a 0.5 inch inner diameter ceramic reactor. H₂Sconversion was calculated based on the H₂ concentration measured using aSiemens CALOMAT 6E H₂ analyzer and intermittently with Interscan's ModelRM17-500m Toxic gas monitor for H₂S concentration. At 400° C. reactortemperature, the H₂S conversion was 32% higher at 1.8 atm compared to 1atm for a GHSV of 4500 hr⁻¹.

Example 8 Performance of Fe—Cr Alloy Material with Ni

Fe—Cr alloy material with Ni was tested in a fixed bed reactor for H₂Sconversion. The sample consisted of 45 wt % Fe—Cr alloy, 10 wt % Ni₃S₂and 45 wt % SiO₂. The Fe—Cr alloy material was used in a powder form ina 0.5 inch inner diameter ceramic reactor, which was heated by anelectrical heater to a temperature of 800° C. H₂S conversion wascalculated by measuring the H₂S concentration in the reactor outletusing Interscan's Model RM17-500m Toxic gas monitor. 0.9% H₂S balancedwith N₂ was reacted with Sample 1 at a GHSV of 3800 hr⁻¹. The maximumH₂S conversion was >90%.

1. A method comprising: contacting a first gaseous input streamcomprising hydrogen sulfide (H₂S) with a metal alloy particle comprisingat least a first metal component comprising a first metal, and a secondmetal component comprising a second metal that is different from thefirst metal, whereupon the hydrogen sulfide (H₂S) in the first gaseousinput stream reacts in a sulfidation reaction with the metal alloyparticle to generate hydrogen gas (H₂) and one or more sulfide minerals,collecting a first gaseous product stream comprising the hydrogen gas(H₂); after collecting the first gaseous product stream, contacting asecond gaseous input stream comprising at least one inert gas with theone or more sulfide minerals, thereby generating sulfur gas andregenerating the metal alloy particle; and collecting a second gaseousproduct stream comprising the sulfur gas.
 2. The method according toclaim 1, wherein the first gaseous input stream further comprises one ormore of CO, H₂, CO₂, and a hydrocarbon feedstock.
 3. The method of claim1, wherein the first metal component comprises the first metal, a firstmetal sulfide comprising the first metal, a first metal oxide comprisingthe first metal, or combinations thereof, and wherein the second metalcomponent comprises the second metal, a second metal sulfide comprisingthe second metal, a second metal oxide comprising the second metal, orcombinations thereof.
 4. The method of claim 1, wherein each of thefirst metal and second metal is selected from the group consisting ofiron (Fe), chromium (Cr), nickel (Ni), Zinc (Zn), cobalt (Co), manganese(Mn) and copper (Cu).
 5. The method of claim 1, wherein the sulfidemineral is selected from the group consisting of a metal sulfide, athiospinel and combinations thereof.
 6. The method of claim 1, whereinthe first metal is iron (Fe) and the second metal is chromium (Cr). 7.The method of claim 5, wherein the sulfide mineral is selected from thegroup consisting of an iron sulfide, a chromium sulfide, andcombinations thereof.
 8. The method of claim 7, wherein the sulfidemineral comprises FeCr₂S₄.
 9. The method of claim 1, wherein the atleast one inert gas is selected from the group consisting of nitrogen,carbon dioxide, air and combinations thereof.
 10. The method of claim 1,wherein the metal alloy particle is a particle having a diameter ofbetween about 100 microns and about 10 mm.
 11. The method of claim 1,wherein the step of contacting the first gaseous input stream with themetal alloy particle is carried out in a sulfidation reactor selectedfrom the group consisting of a fixed bed reactor, a fluidized bedreactor, a co-current moving bed reactor and a counter-current movingbed reactor.
 12. The method of claim 11, wherein the molar ratio ofgases:solids within the sulfidation reactor during the step ofcontacting the first gaseous input stream with the metal alloy particleis between about 0.2 to about
 10. 13. The method of claim 1, wherein thestep of contacting the first gaseous input stream with the metal alloyparticle is carried out at a first temperature between about 100° C. andabout 950° C., and a first pressure between about 1 atm and about 150atm.
 14. The method of claim 13, wherein the first temperature isbetween about 300° C. and about 450° C.
 15. The method of claim 1,wherein the step of contacting the second gaseous input stream with theone or more sulfide minerals is carried out in a regeneration reactorselected from the group consisting of a fixed bed reactor, a fluidizedbed reactor, a co-current moving bed reactor and a counter-currentmoving bed reactor.
 16. The method of claim 15, wherein the molar ratioof gases:solids within the regeneration reactor during the step ofcontacting the second gaseous input stream with the one or more sulfideminerals is between about 0.2 to about
 10. 17. The method of claim 1,wherein the step of contacting the second gaseous input stream with theone or more sulfide minerals is carried out at a second temperaturebetween about 500° C. and about 1100° C., and a second pressure betweenabout vacuum conditions and about 150 atm.
 18. The method of claim 1,wherein the first gaseous product stream comprises less than 100 ppmvH₂S.
 19. The method of claim 1, further comprising after collecting thesecond gaseous product stream, contacting the regenerated metal alloywith a subsequent first gaseous input stream such that a hydrogen gas(H₂) production performance of the regenerated metal alloy particle issimilar to a hydrogen gas (H₂) production performance of the metal alloyparticle.
 20. The method of claim 1, wherein contacting the firstgaseous input stream and contacting the second gaseous input stream isperformed in a batch operational mode, in a semibatch operational mode,or in a continuous operational mode.
 21. The method of claim 1, whereinthe first gaseous input stream does not include oxygen (O₂).
 22. A metalalloy particle for use in a method of converting H₂S to hydrogen (H₂)and sulfur, the metal alloy particle comprising a first metal component,a second metal component, and at least one secondary material, whereinthe first metal component comprises iron, the second metal componentcomprises chromium, and the at least one secondary material ismolybdenum, nickel, cobalt, manganese, tungsten, vanadium or acombination thereof.
 23. The metal alloy particle of claim 22, whereinthe metal alloy particle further comprises one or more supportmaterials.
 24. The metal alloy particle of claim 22, wherein the firstmetal component comprises an iron sulfide and the second metal componentcomprises a chromium sulfide.
 25. The metal alloy particle of claim 22,wherein the at least one secondary material is a molybdenum sulfide, anickel sulfide, a cobalt sulfide, a manganese sulfide, a tungstensulfide, vanadium sulfide or a combination thereof.
 26. The metal alloyparticle of claim 22, wherein the metal alloy particle comprises 10-95%by weight of the first metal component, 5-80% of the second metalcomponent, and 1-50% by weight of the at least one secondary material.27. The metal alloy particle of claim 22, wherein the metal alloycomprises a support material selected from Al₂O₃, SiO₂, TiO₂, and ZrO₂.28. A method of producing the metal alloy particle of claim 22, themethod comprising mixing the first metal component with the second metalcomponent to produce a mixture, contacting the mixture with a gas streamcomprising H₂S to produce a reacted mixture, passing nitrogen over thereacted mixture to form a bimetallic alloy, and mixing one or moresecondary materials and optionally one or more support materials withthe bimetallic alloy to produce the metal alloy.